The present invention introduces a new phased array, called the peripherally-excited phased array (PEX-PA). The PEX-PA comprises an electrically large metallic cavity which is excited by weighted antenna sources only at its periphery. The top surface of the cavity is patterned with a suitable configuration of apertures (slots) whereas the cavity is filled with a dielectric material. The (PEX-PA) is capable of beam scanning, one or multiple beams, over a large number of directions in air but with a drastically reduced number of passive or active phase shifters. Specifically, the PEX-PA scales the number of phase-shifters according to the circumference of the cavity and not its area, as usually the case in a conventional phased array.